Quantum mechanics is deeply rooted in the heart of modern physics. But it is not easy to teach. Quantum theory often contradicts our everyday life experience and the corresponding experiments are neither easy to setup nor to maintain.When Aspect, Roger and Dalibard showed that entangled photons violate Bell’s inequality for the first time in 1982, their setup filled the whole basement lab. The quEDfits on any lab desk and can be set up in minutes. And it is more accurate and a lot more efficient than the apparatus of Aspect and his colleagues.

qutools’ Entanglement Demonstrator is designed for educational purposes. The easy-to-use system frees the hands and brains of anyone trying to explain the complex phenomena of quantum mechanics. Because that’s already hard enough.

quED: “Spooky action at a distance”? Not so spooky anymore…

It’s a science project kit for modern physics.

Sample Experiments

Here is a list of the experiments you can do with the quED and its add-ons.

Single Photon Experiments without Interference

Particle Nature of Photons

Quantum Cryptography/QKD: BB84 Protocol

Tomographic Single Photon State Reconstruction

Quantum Zeno Effect

Quantum Random Number Generation

Single Photon Experiments with Interference

Wave Nature of Photons: Single Photon Michelson Interferometer

Quantum Eraser

Wave-Particle Dualism: Michelson + HBT

Double Michelson Interferometer

Visible (White) Light Interference (Observable by Eye)

Measurement of the Central Wavelength of Single Photons

Measurement of Coherence Length of Single Photons

Interaction-Free Measurement (Bomb Test)

Photon Pair Experiments with Polarisation Entanglement

Violation of Bell’s Inequality (CHSH)

“Non-Classical” Polarisation Correlations

Tomographic State Reconstruction of an Entangled Photon State

Quantum Cryptography/QKD: BBM Protocol

Quantum Cryptography: Ekert Protocol

Photon Pair Experiments without Polarisation Entanglement

Hong-Ou-Mandel 2-Photon Interference

Hong-Ou-Mandel Interference + Hanbury Brown & Twiss

Franson Interference

These are the experiments we have come up with so far and found interesting enough to put them here. Do you have more ideas? Please let us know!

The functionality of the quED system can easily be extended with three add-ons:

+ quED-MI Michelson Interferometer

Demonstrate the wave nature of single photons through their interference or build a quantum eraser.

Single Photon Michelson Interferometer Add-On for the quED.

Single Photon Michelson Interferometer Add-On for the quED.

Interference is generally considered to be a wave phenomenon. Curiously it also works with single quantum objects. Use the quED-MI Michelson Interferometer add-on together with the quED to show that this is the case. (The photograph shows the motorised version.)

Perform the “Grangier Experiment”, explore the particle nature of single photons with a Hanbury Brown & Twiss setup and build a quantum random bit generator.

Hanbury Brown & Twiss Setup for Heralded Single Photon Sources.

Hanbury Brown-Twiss setup Add-On for the quED

Photons (or generally quantum objects) sometimes also behave like particles. With this add-on you can show that photons can not be split up. You can also explore a simple quantum random bit/number generator and use it in combination with the quED-MI to show wave and particle nature of photons in one experiment.

Hong-Ou-Mandel Interferometer Demonstrating 2-Photon Interference.

Hong-Ou-Mandel effect Add-On for the quED

When you have two indistinguishable photons and each of them hit one input of a beam splitter, they exit the beam splitter together in one output port. This is an effect you cannot demonstrate with bright light, but with this add-on you can.

Securely distribute a secret key between Alice and Bob with the BB84 protocol.

Quantum Cryptography Add-On for the quED.

One of the most popular industrial applications for quantum phenomena right now is quantum cryptography, or better, quantum key distribution. With this add-on, you can use weak coherent pulses to simulate realistically how a secure communication between two parties (Alice and Bob) is made possible by the BB84 protocol in a real environment.

Key Features

The quED design combines recent achievements of quantum optics technology into an easy-to-use system for academic, research and applied purposes with precise accuracy. Advanced models for scientific purposes are available as well, with a high performance meeting the requirements of state-of-the-art physics experiments.

Hands-on study of quantum entanglement

Compact design, user-friendly operation

Complete system: Ready to violate Bell’s inequalities

High performance: Entanglement verification in only a few seconds

Optional: Add-ons to extend the number of experiments

References

George Musser, editor at Scientific American magazine and the author “Spooky Action at a Distance” and “The Complete Idiot’s Guide to String Theory” about the quED: “Do-it-yourself quantum spooky action! An experiment that used to fill a basement lab now fits on any table.”

Dr. Eleni Diamanti, Université Pierre et Marie Curie, Paris: “We use the quED in my laboratory as a central element for our teaching activities; it is always a great and guaranteed success thanks to its stability and reliability. We have also extensivley used it in experiments ranging from the demonstration of nonlocal quantum games (Phys. Rev. Lett. 2015) to the reference-frame-independent quantification of bipartire entanglement (Phys. Rev. A 2014), more experiments are underway. “

Dr. Ulrich Busk Hoff, Danmarks Tekniske Universitet: “At DTU Physics we are proud to have high-quality products from qutools which allow us to do engaging outreach and hands-on teaching of fundamental quantum physics. The quED is an impressive product that puts everyone in a position to experiment with quantum physics. Thanks to our setups from qutools, Bell’s inequality has finally been violated for the first time in Denmark.”

Applications

qutools’ Entanglement Demonstrator is designed with educators in mind. It’s the easiest and most reliable way to explain the complex phenomena of quantum mechanics by generating and analysing polarization-entangled photon pairs.

Specific applications are:

Student lab course experiments

Demonstration experiments in lectures

Hands-on experiments for science centers

Project kits for students’ research centers

For demonstration experiments, we propose to use the motorised version. When students are supposed to perform the experiments themselves, the manual versions are recommended.

System Includes

The standard quED package includes everything you need to violate Bell’s inequality and perform similar experiments.